Backside contact structures and fabrication for metal on both sides of devices

ABSTRACT

An apparatus including a circuit structure including a device stratum including a plurality of devices including a first side and an opposite second side; and a metal interconnect coupled to at least one of the plurality of devices from the second side of the device stratum. A method including forming a transistor device including a channel between a source region and a drain region and a gate electrode on the channel defining a first side of the device; and forming an interconnect to one of the source region and the drain region from a second side of the device.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a U.S. National Phase Application under 35U.S.C. § 371 of International Application No. PCT/US2015/052440, filedSep. 25, 2015, entitled “BACKSIDE CONTACT STRUCTURES AND FABRICATION FORMETAL ON BOTH SIDES OF DEVICES,” which designates the United States ofAmerica, the entire disclosure of which is hereby incorporated byreference in its entirety and for all purposes.

TECHNICAL FIELD

Semiconductor devices including devices having electrical connectionsfrom a backside of the device.

BACKGROUND

For the past several decades, the scaling of features in integratedcircuits has been a driving force behind an ever-growing semiconductorindustry. Scaling to smaller and smaller features enables increaseddensities of functional units on the limited real estate ofsemiconductor chips. For example, shrinking transistor size allows forthe incorporation of an increased number of memory devices on a chip,lending to the fabrication of products with increased capacity. Thedrive for ever-more capacity, however, is not without issue. Thenecessity to optimize the performance of each device becomesincreasingly significant.

Future circuit devices, such as central processing unit devices, willdesire both high performance devices and low capacitance, low powerdevices integrated in a single dye or chip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top side perspective view of a three-dimensionaltransistor device formed on a fin on a portion of a silicon orsilicon-on-insulator (SOI) substrate.

FIGS. 2A-2C show cross-sectional side views through FIG. 1.

FIG. 3 shows the structure of FIG. 1 following the forming of contactsand interconnects to the three-dimensional transistor device structure.

FIGS. 4A-4C show cross-sectional side views through the structure ofFIG. 2.

FIGS. 5A-5C show the structure of FIG. 3 following the inverting orflipping of the structure and connection of the structure to a carrier.

FIGS. 6A-6C show the structure of FIGS. 5A-5C following the removal orthinning of the transistor device substrate to expose a second side orbackside of fin of the transistor device.

FIGS. 7A-7C show the recessing of the fin.

FIGS. 8A-8C shows the structure of FIGS. 7A-7C following the depositionand patterning of a dielectric material on a backside of the fin of thetransistor device with openings to source and drain regions.

FIGS. 9A-9C show the structure of FIGS. 8A-8C following an epitaxialgrowth of a material for a backside junction formation in the backsideopenings to source and drain regions.

FIGS. 10A-10C show the structure of FIGS. 9A-9C following the filling ofthe via openings in dielectric material 180 with a conductive contactmaterial.

FIGS. 11A-11C shows the structure of FIGS. 10A-10C and show aninterconnect connected to the contact to the source of the transistordevice as part of a first backside interconnect or metal layer.

FIGS. 12A-12C show the structure of FIGS. 8A-8C following a depositionof a doped epitaxial material in the openings to source and drainregions according to another embodiment for forming contacts to devicesfrom a backside of such devices.

FIGS. 13A-13C show the structure of FIGS. 12A-12C following the drive-inof dopants from the epitaxial material into the fin in source and drainregions of the device.

FIGS. 14A-14C show the structure of FIGS. 13A-13C following the optionalremoval of the epitaxial material after a dopant drive-in process.

FIGS. 15A-15C show the structures of FIGS. 14A-14C following theintroduction of contact metal in the regions aligned with source anddrain.

FIGS. 16A-16C show the structure of FIGS. 8A-8C following theintroduction of an implant into regions of a fin of the device alignedwith source and drain regions according to another embodiment of forminga contact to a device from a backside of a device structure.

FIGS. 17A-17C show the structures of FIGS. 16A-16C following theintroduction of contact metal in the regions aligned with the source anddrain of the device.

FIG. 18 shows a top side perspective view of three-dimensionaltransistor device formed on a fin on a portion of a semiconductor orsemiconductor-on-insulator (SOI) substrate according to anotherembodiment where sacrificial material is introduced at a base of the finin source and drain regions.

FIGS. 19A-19C show cross-sectional side views through the structure ofFIG. 18.

FIGS. 20A-20C show the structure of FIGS. 19A-19C following theintroduction of a dielectric material on the first level interconnects;the inverting or flipping of the structure and connection of thestructure to a carrier; the thinning of the substrate and recessing ofthe fin; and the defining of regions of the fin for backside connectionto the source and drain of the device.

FIGS. 21A-21C show the structure of FIGS. 20A-20C following the removalof the sacrificial material adjacent opposing sidewalls of the fin insource and drain regions.

FIGS. 22A-22C show the structure following an epitaxial growth of amaterial for a backside junction formation and contacts formed on abackside of the device.

FIG. 23 shows a cross-sectional schematic side view of one embodiment ofan assembly including an integrated circuit chip or die connected to apackage substrate.

FIG. 24 is a flow chart of a process to form contacts to source anddrains of a three dimensional transistor device from a backside andbackside metallization.

FIG. 25 is an interposer implementing one or more embodiments.

FIG. 26 illustrates an embodiment of a computing device.

DETAILED DESCRIPTION

The embodiments described herein are directed to semiconductor devicesincluding interconnects or wiring below or on a backside of the devices.Such embodiments are achieved by using backside reveal and backsideprocessing. The embodiments described include an apparatus including acircuit structure including a device layer or stratum including aplurality of devices having a first side and an opposite second side anda metal interconnect connected to at least one of the plurality ofdevices from the second side of the stratum. Embodiments for formingsuch devices are also described including examples of backside epitaxialdeposition, backside implant and backside epitaxial deposition anddrive-in. Backside reveal processing allows flexibility in the type ofconnections that can be fabricated.

FIGS. 1-10C describe a method or process of forming a non-planarmulti-gate semiconductor device including electrical connections on anon-device side or backside of the structure. In one embodiment, thedevice is a three-dimensional metal oxide semiconductor field effecttransistor (MOSFET) and is an isolated device or is one device in aplurality of nested devices. As will be appreciated, for a typicalintegrated circuit, both N- and P-channel transistors may be fabricatedon a single substrate to form a complimentary metal oxide semiconductor(CMOS) integrated circuit. Furthermore, additional interconnects may befabricated in order to integrate such devices into an integratedcircuit.

In the fabrication of non-planar transistors, such as multi-gatetransistors and FinFETs, non-planar semiconductor bodies may be used toform transistors generally capable of full depletion with relativelysmall gate lengths (e.g., less than about 30 nm). These semiconductorbodies are generally fin-shaped and are, thus, generally referred to astransistor “fins”. For example in a tri-gate transistor, the transistorfin has a top surface and two opposing sidewalls formed on a bulksemiconductor substrate or a silicon-on-insulator substrate. A gatedielectric may be formed on the top or superior surface and sidewalls ofthe semiconductor body and a gate electrode may be formed over the gatedielectric on the top or superior surface of the semiconductor body andadjacent to the gate dielectric on the sidewalls of the semiconductorbody. Since the gate dielectric and the gate electrode are adjacent tothree surfaces of the semiconductor body, three separate channels andgates are formed. As there are three separate channels formed, thesemiconductor body can be fully depleted when the transistor is turnedon. With regard to finFET transistors, the gate material and theelectrode contact the sidewalls of the semiconductor body, such that twoseparate channels are formed.

FIG. 1 shows a top side perspective view of a portion of a semiconductoror semiconductor-on-insulator (SOI) substrate that is, for example, aportion of an integrated circuit die or chip on a wafer. Specifically,FIG. 1 shows structure 100 including substrate 110 of silicon or SOI.Overlaying substrate 110 is optional buffer layer 120. In oneembodiment, a buffer layer is a silicon germanium buffer introduced, inone embodiment, on substrate 110 by a growth technique.Representatively, buffer layer 120 has a representative thickness on theorder of a few hundred nanometers (nm).

Disposed on a surface of substrate 110 and optional buffer layer 120 inthe embodiment illustrated in FIG. 1 (an upper surface as viewed), is aportion of a transistor device such as an N-type transistor device or aP-type transistor device. Common to an N-type or P-type transistordevice, in this embodiment, is body or fin 130 disposed on a surface ofbuffer layer 120. In one embodiment, fin 130 is formed of asemiconductor material such as silicon, silicon germanium or a groupIII-V or group IV-V semiconductor material. In one embodiment, amaterial of fin 130 is formed according to conventional processingtechniques for forming a three-dimensional integrated circuit device.Representatively, a semiconductor material is epitaxially grown on thesubstrate and then formed into fin 130 (e.g., by a masking and etchprocess).

In one embodiment, fin 130 has a length dimension, L, greater than aheight dimension, H. A representative length range is on the order of 10nanometers (nm) to 1 millimeter (mm), and a representative height rangeis on the order of 5 nm to 200 nm. Fin 130 also has a width, W,representatively on the order of 4-10 nm. As illustrated, fin 130 is athree-dimensional body extending from or on a surface of substrate 110(or optionally from or on buffer layer 120). The three-dimensional bodyas illustrated in FIG. 1 is a rectangular body with opposing sides(first and second sides) projecting from a surface of buffer layer 120as viewed. It is appreciated that in processing of such bodies, a truerectangular form may not be achievable with available tooling, and othershapes may result. Representative shapes include, but are not limitedto, a trapezoidal shape (e.g., base wider than top) and an arch shape.

Disposed on fin 130 in the embodiment of a structure of FIG. 1 is a gatestack. In one embodiment, a gate stack includes a gate dielectric layerof, for example, silicon dioxide or a dielectric material having adielectric constant greater than silicon dioxide (a high k dielectricmaterial). Disposed on the gate dielectric layer, in one embodiment, isgate 125 of, for example, a metal. The gate stack may include spacers150 of dielectric material on opposite sides thereof. A representativematerial for spacers 150 is a low k material such as silicon nitride(SiN) or silicon carbon nitrogen (SiCN). FIG. 1 shows spacers 150adjacent the sidewalls of the gate stack and on the fin 130. Formed onor in fin 130 on opposite sides of the gate stack are junction regions(source 140A and drain 140B).

In one embodiment, to form the three-dimensional transistor structure, agate dielectric material is formed on fin 130 such as by way of ablanket deposition followed by a blanket deposition of a sacrificial ordummy gate material. A mask material is introduced over the structureand patterned to protect the gate stack material (gate stack withsacrificial or dummy gate material) over a designated channel region. Anetch process is then used to remove the gate stack material in undesiredareas and pattern the gate stack over a designated channel region.Spacers 150 are then formed. One technique to form spacers 150 is todeposit a film on the structure, protect the film in a desired area andthen etch to pattern the film into desired spacer dimensions.

Following the formation of a gate stack including a sacrificial or dummygate material on fin 130 and spacers 150, junction regions (source anddrain) are formed on or in fin 130. The source and drain are formed infin 130 on opposite sides of the gate stack (sacrificial gate electrodeon gate dielectric). In the embodiment shown in FIG. 1, source 140A anddrain 140B are formed by epitaxially growing source and drain materialas a cladding on a portion of fin 130. Representative material forsource 140A and drain 140B includes, but is not limited to, silicon,silicon germanium, or a Group III-V or Group IV-V compound semiconductormaterial. Source 140A and drain 140B may alternatively be formed byremoving portions of the fin material and epitaxially growing source anddrain material in designated junction regions where fin material wasremoved.

Following the formation of source 140A and drain 140B, in oneembodiment, the sacrificial or dummy gate is removed and replaced with agate electrode material. In one embodiment, prior to removal of thesacrificial or dummy gate stack, a dielectric material is deposited onthe structure. In one embodiment, dielectric material is silicon dioxideor a low k dielectric material deposited as a blanket and then polishedto expose sacrificial or dummy gate 125. The sacrificial or dummy gateand gate dielectric are then removed by, for example, an etch process.

Following a removal of the sacrificial or dummy gate and gatedielectric, a gate stack is formed in a gate electrode region. A gatestack is introduced, e.g., deposited, on the structure including a gatedielectric and gate electrode. In an embodiment, gate electrode 125 ofthe gate electrode stack is composed of a metal gate and a gatedielectric layer is composed of a material having a dielectric constantgreater than a dielectric constant of silicon dioxide (a high-Kmaterial). For example, in one embodiment, gate dielectric layer 127(see FIGS. 2A-2C) is composed of a material such as, but not limited to,hafnium oxide, hafnium oxy-nitride, hafnium silicate, lanthanum oxide,zirconium oxide, zirconium silicate, tantalum oxide, barium strontiumtitanate, barium titanate, strontium titanate, yttrium oxide, aluminumoxide, lead scandium tantalum oxide, lead zinc niobate, or a combinationthereof. In one embodiment, gate electrode 125 is composed of a metallayer such as, but not limited to, metal nitrides, metal carbides, metalsilicides, metal aluminides, hafnium, zirconium, titanium, tantalum,aluminum, ruthenium, palladium, platinum, cobalt, nickel or conductivemetal oxides. Following the formation of the gate stack, additionaldielectric material dielectric material of silicon dioxide or a low kdielectric material is deposited on the three-dimensional transistordevice (e.g., on ILD0) to encapsulate or embed the device structure indielectric material. FIG. 1 shows dielectric material 155A encapsulatingthe three-dimensional transistor device (e.g., as an ILD0).

FIGS. 2A-2C show cross-sectional side views through FIG. 1. Morespecifically, FIG. 2A shows a cross-sectional side view through lineA-A′ of FIG. 1 which is a cross-section through fin 130; FIG. 2B shows across-section through line B-B′ which is a cross-section through source140A; and FIG. 2C shows a cross-section through line C-C′ which is across-section through gate electrode 125. The same orientation ofcross-sections (A-C) will be presented throughout this description. FIG.3 shows the structure of FIG. 1 following the forming of interconnectsto the three-dimensional transistor device structure. In thisembodiment, an electrical connection is made as a first interconnectlayer or metal layer to source 140A, drain 140B and gate electrode 125.Representatively, to form individual electrical contacts to source 140A,drain 140B and gate electrode 175, openings are initially formed to thesource and gate electrode by, for example, a masking process withopenings to each of source 140A, drain 140B and gate electrode 125. Thedielectric material is etched to expose the source and gate electrodeand then the masking material removed. Next, a contact material of, forexample, tungsten is introduced in the openings and the openings arefilled to form contact 165A to source 140A, contact 165B to drain 140Band contact 175 to gate electrode 125. A surface of dielectric material155 (a top surface as viewed) may then be seeded with a conductive seedmaterial and then patterned with masking material to define openings forinterconnect paths with respective openings exposing contact 165A,contact 165B and contact 175. A conductive material such as copper isthen introduced by way of an electroplating process to form interconnect160A connected to contact 165A to source 140A, interconnect 160Bconnected to contact 165B and interconnect 170 connected to contact 175of gate electrode 125. The masking material and unwanted seed materialcan then be removed. Following the formation of interconnects as aninitial metal layer, dielectric material 155B of for example, silicondioxide or a low k dielectric material may be deposited as an ILD1 layeron and around the interconnects. Additional interconnect layers may thenbe formed according to conventional processes.

FIGS. 4A-4C show cross-sectional side views through the structure ofFIG. 2. Specifically, FIG. 4A shows a cross-section through line A-A′through fin 130; FIG. 4B shows a cross-section through line B-B′ throughsource 140A; and FIG. 4C shows a cross-sectional side view through lineC-C′ through gate electrode 125. In the illustration shown in FIG. 3 andFIGS. 4A-4C, a first level of interconnects is formed and connected to atransistor device on substrate 110. It is appreciated that additionalinterconnect or metallization levels may be formed on this first levelby techniques known in the art. The operations that follow thuscontemplate a structure (structure 100) that has one or more levels ofinterconnects or metallization on a device side of the structure (adevice side of a device stratum).

FIGS. 5A-5C show the structure of FIG. 3 following the inverting orflipping of the structure and connection of the structure to a carrier.FIGS. 5A-5C represent cross-sections through fin 130, drain 140B, andgate electrode 125, respectively, as described above with respect toFIGS. 2A-2C and FIGS. 4A-4C. Referring to FIGS. 5A-5C, in thisembodiment, structure 100 is flipped and connected to carrier 180.Carrier 180 is, for example, a semiconductor wafer. Structure 100 may beconnected to carrier 180 through an adhesive or other bonding technique.

FIGS. 6A-6C show the structure of FIGS. 5A-5C following the removal orthinning of substrate 110 to expose a second side or backside of fin130. In one embodiment, substrate 110 may be removed by a thinningprocess, such as a mechanical grinding or etch process. FIGS. 6A-6C showfin 130 exposed from a second side or backside of the structure.Following exposure of fin 130, the fin may optionally be recessed. FIGS.7A-7C show the structure of FIGS. 6A-6C following a recessing of fin130. In one embodiment, to recess fin 130, an etch process may beutilized with an etchant selective toward a removal of fin materialrelative to dielectric material 155A. Alternatively, a masking materialmay be patterned on a surface of dielectric material 155 (an exposedbackside surface) with an opening that exposes fin 130. A material offin 130 may optionally be removed to recess fin 130 by, for example, anetch process, and then the masking material removed.

FIGS. 8A-8C shows the structure of FIGS. 7A-7C following the depositionand patterning of a dielectric material on a backside of fin 130. FIGS.8A-8C show dielectric material 181 of, for example, a silicon dioxide ora low K dielectric material deposited by for example, a blanketdeposition process. Once deposited, dielectric material 181 may bepatterned by, for example, forming a masking material on a surface ofdielectric material 180 with openings or vias opposite, for example,source and drain regions on an opposite side of fin 130. FIG. 8A showsopening 182A through dielectric material 181 oriented on a backside offin 130 corresponding to a source region of the fin (source 140A) andopening 182B through dielectric material 181 oriented to a drain regionof the fin (drain 140B). FIG. 8B shows that the openings (e.g., opening182A) have dimensions for a diameter that is greater than a widthdimension of fin 130. In this manner, a backside of fin 130 as well asside walls of fin 130 are exposed. FIG. 8B also shows that the etchproceeds through the structure to expose a backside of source 140A. Thepatterning of dielectric material to form opening 182A and opening 182B,in one embodiment, such that each opening has a dimension to expose abackside of source 140A and drain 140B, respectively, to allow amaterial to make contact with the source and drain and representativelyallow epitaxial growth thereon as described in the following operations.

FIGS. 9A-9C show the structure of FIGS. 8A-8C following an epitaxialgrowth of a material for a backside junction formation. FIG. 9A showsepitaxially grown material 185A in opening 182A in a region aligned witha backside of source 140A and epitaxially grown material 185B in opening182B on fin 130 aligned with a backside of drain 140B. FIG. 9B showsmaterial 185A epitaxially grown on the side walls of fin 130 andconnecting with source 140A previously formed on a first side or deviceside of the structure. In one embodiment, a material for material 185Aand material 185B is similar to that of source 140A and drain 140B(e.g., silicon, silicon germanium, or a Group III-V or a Group IV-Vcompound semiconductor materials).

FIGS. 10A-10C show the structure of FIGS. 9A-9C following the filling ofthe via openings in dielectric material 180 with a conductive contactmaterial such as a tungsten. FIG. 10A shows contact 186A to epitaxialmaterial 185B associated with source 140A and contact metal 186B toepitaxial material 185B associated with drain 140B. FIG. 10B showscontact metal 186B to epitaxial material 185B. FIGS. 10A and 10B alsoshow the connection to source 140A (via contact material) from opposingsides of the structure (a first side or device side and a backside orsecond side) respectively. Interconnects may now be formed to contacts186A and 186B by, for example, the technique described above withrespect to device side interconnects (see FIGS. 3 and 4A-4C and theaccompanying text). FIGS. 11A-11C shows the structure of FIGS. 10A-10Cand show interconnect 190A connected to contact 196A to source 140A aspart of, for example, a first backside interconnect or metal layer.FIGS. 11A-11C also show the structure following the deposition ofdielectric material 155C of silicon dioxide or a low k dielectricmaterial on the interconnect or metal layer. Following the deposition ofdielectric material 155C, one or more additional interconnect levels maybe introduced on the dielectric material through, for example,electroplating techniques, and connected to devices or underlyinginterconnects as known in the art.

FIGS. 12A-12C illustrate an alternative embodiment for forming contactsto devices from a backside of such devices. In this example, rather thanepitaxial deposition in contact areas around the fin, an epitaxialdeposition of doped epitaxial material is followed by dopant drive-in tomodify portion of the fin in a contact area. FIGS. 12A-12C show thestructure of FIGS. 8A-8C described above with respect to the previousembodiment.

FIGS. 13A-13C show epitaxial material 285 introduced in opening 182A ofdielectric material 181 and opening 182B of dielectric material 181aligned on a backside of the device to source 140A and drain 140B,respectively. A suitable material for epitaxial material 285 is asilicon germanium material for a PMOS device and a silicon material foran NMOS device. Other suitable materials for epitaxial material 285 fora PMOS or an NMOS device include silicon, germanium, silicon germanium,silicon-germanium-carbon, carbon-doped silicon (NMOS only),germanium-tin and Group III-V compound semiconductor materials such asgallium arsenide, indium arsenide, indium-gallium arsenide, indiumphosphide and gallium nitride.

FIGS. 13A-13C show the structure of FIGS. 12A-12C following the drive-inof dopants from epitaxial material 285 into fin 130 from a backside inregions aligned with source 140A and drain 140B. One technique todrive-in dopants is a thermal process. Representatively, for anepitaxial material of phosphorous-doped silicon (for NMOS) andboron-doped silicon (for PMOS), a thermal drive-in representativelyinvolves heating the structure to a temperature of 800 to 1100° C. for aperiod sufficient to allow dopants to migrate from the epitaxialmaterial into fine 130. FIGS. 13A-13C show regions of fin 130 modifiedwith dopants 284.

FIGS. 14A-14C show the structure of FIGS. 13A-13C following the optionalremoval of epitaxial material 285A in opening 182A and opening 182B,respectively, after a dopant drive-in process. FIGS. 15A-15C show thestructures of FIGS. 14A-14C following the introduction (e.g.,deposition) of contact metal in the regions aligned with and connectedto source 140A and drain 140B, respectively. FIG. 15A shows contactmetal 286A and contact metal 286B of, for example, tungsten, in contactwith modified portions of fin 130 (modified with dopants) where suchregions are aligned with source 140A and drain 140B. FIG. 15B showscontact metal 286A disposed along opposite sidewalls of modified portion284 and in contact with source 140A. After forming contacts,interconnects or metal lines may be formed to the contacts on thebackside of the device as described above with respect to FIGS. 11A-11Cand the accompanying text.

FIGS. 16A-16C describe another embodiment of forming a contact to adevice from a backside of a device structure. FIGS. 16A-16C show thestructure of FIGS. 8A-8C, respectively, the structure being formed, inone embodiment, according to the operations described up to andincluding FIGS. 8A-8C. In FIGS. 16A-16C, an implant is introduced from abackside into fin 130 in regions aligned with or opposite (from abackside perspective) source 140A and drain 140B, respectively. FIG. 16Ashows an implant process introducing implant material 385 of, forexample, arsenic/phosphorous for an NMOS device or boron for a PMOSdevice.

FIGS. 17A-17C show the structures of FIGS. 16A-16C following theintroduction (e.g., deposition) of contact metal in the regions alignedwith source 140A and drain 140B. FIG. 17A shows contact metal 386A andcontact metal 386B of, for example, tungsten, in contact with modifiedportions of fin 130 (modified with implants) where such regions arealigned with and connected to source 140A and drain 140B, respectively.FIG. 17B shows contact metal 386A disposed along opposite sidewalls ofmodified portion 384 and contact with source 140A. After formingcontacts, interconnects or metal lines may be formed to the contacts onthe backside of the device as described above with respect to FIGS.11A-11C and the accompanying text.

FIGS. 16A and 16B show fin 130 modified with implant material 384. FIGS.17A-17C show the structure of FIGS. 16A-16C following the introduction(e.g., deposition) of contact metal in the regions aligned with source140A and drain 140B and having implant-modified portions of fin 130.FIG. 17A shows contact metal 386A and contact metal 386B of, forexample, tungsten, in contact with implant-modified portions of fin 130where such regions are aligned and connected to source 140A and drain140B, respectively. FIG. 17B shows contact metal 386A disposed alongsidewalls of implant-modified portion 384 of fin 130 and in contact withsource 140A. Following the formation of contacts to a backside of thedevice, interconnects or metal lines may be formed to the contacts asdescribed above in the previous embodiments (see FIGS. 11A-11C and theaccompanying text).

FIGS. 18-22C describe another embodiment of a method or process offorming a non-planar multi-gate semiconductor device includingelectrical connections on a non-device side or backside of thestructure. FIG. 18 shows a top side perspective view of a portion of asemiconductor or semiconductor-on-insulator (SOI) substrate that is, forexample, a portion of an integrated circuit die or chip on a wafer.Specifically, FIG. 18 shows structure 400 including substrate 410 ofsilicon or SOI. Overlaying substrate 410 is optional buffer layer 420such as silicon germanium.

Disposed on a surface of substrate 410 and optional buffer layer 420 inthe embodiment illustrated in FIG. 18 (an upper surface as viewed), is aportion of a transistor device such as an N-type transistor device or aP-type transistor device. Common to an N-type or P-type transistordevice, in this embodiment, is body or fin 430 disposed on a surface ofsubstrate 410 or on buffer layer 420, if present. In one embodiment, fin430 is formed of a semiconductor material such as silicon, silicongermanium or a group III-V or group IV-V semiconductor material.

As illustrated, fin 430 is a three-dimensional body extending from or ona surface of substrate 410 (or optionally from or on buffer layer 420)and has a height dimension, H, a length dimension, L, greater than theheight dimension and a width dimension. Following a formation of fin 430from or on substrate 410 or optionally buffer layer 420, sacrificialmaterial 453 is introduced (e.g., deposited) along a portion of opposingsidewalls of the fin. As illustrated in FIG. 18, sacrificial material453 is disposed on opposing sidewalls of fin 430 in regions along alength dimension designated for junctions (source and drain).Sacrificial material 453 is disposed along a height dimension of fin 430below a region where junctions are formed on or in the fin. In oneembodiment, a three-dimensional transistor device including fin 430 willbe embedded in dielectric material such as silicon dioxide or a low Kdielectric material. When fin 430 is formed, the fin is exposed. At thatpoint, sacrificial material 453 may be introduced by way of a blanketdeposition along a base of fin 430 to a height, h, below portions of fin430 where junctions are to be formed. A representative height, h, ofsacrificial material is on the order of 10 nanometers (nm) to 100 nm. Inone embodiment, wherein fin 430 will later be recessed, a layer ofdielectric material of silicon dioxide or a low k dielectric may beintroduced at a base of fin 430 followed by an introduction ofsacrificial material 453. Sacrificial material 453 may ultimately beremoved to make connections to the source and drain of the transistordevice from a backside of the device. In one embodiment, a material forsacrificial material 453 is a material that meets thermal stabilityrequirement for the processing environment and may be selectively etchedrelative to a dielectric material (e.g., SiO₂) that will ultimatelyembed the device and a material of fin 430. A representative materialfor sacrificial material 453 is a dielectric material such as a siliconnitride (SiN) or titanium nitride (TiN). Once sacrificial material 453is introduced, the material is patterned to a thickness, t, such thatwhen sacrificial material 453 is later removed, sidewalls of fin 430 areexposed from a backside of the structure as is a respective source anddrain allowing contact and/or epitaxial growth from the source anddrain.

Following the formation of sacrificial material 453 on fin 430, atransistor device may be formed as described above with reference toFIG. 1 and the accompanying text. A transistor device, in thisembodiment, includes a gate dielectric layer of, for example, silicondioxide or a dielectric material having a dielectric constant greaterthan silicon dioxide (a high k dielectric material) and gate 425 of, forexample, a metal disposed on fin 430. The gate stack may include spacers450 of dielectric material on opposite sides thereof. A representativematerial for spacers 450 is a low k material such as silicon nitride(SiN) or silicon carbon nitrogen (SiCN). Formed on or in fin 430 onopposite sides of the gate stack are junction regions (source 440A anddrain 440B). In this embodiment, source 440A and drain 440B are formedas cladding on a top and sidewalls of fin 430. Source 440A and source440B have a height dimension along the sidewalls that extends, in oneembodiment, to a depth of sacrificial material 453.

FIG. 18 shows structure 400 following the embedding of the transistordevice in dielectric material 455A (e.g., ILD0) and the forming ofinterconnects to the three-dimensional transistor device structure. Inthis embodiment, an electrical connection is made as a firstinterconnect layer or metal layer to source 440A, drain 440B and gateelectrode 425. FIG. 18 shows a contact material of, for example,tungsten is introduced in openings or vias of dielectric material 455 toform contact 465A to source 440A, contact 465B to drain 440B and contact475 to gate electrode 425. FIG. 18 also shows a first metal orinterconnect line or layer on a surface of dielectric material 455including interconnect 460A connected to contact 465A to source 440A,interconnect 460B connected to contact 465B and interconnect 470connected to contact 475 of gate electrode 425. Following the formationof interconnects as an initial metal layer, a dielectric material of forexample, silicon dioxide or a low k dielectric material may be depositedas an ILD1 layer on and around the interconnects. Additionalinterconnect layers may then be formed according to conventionalprocesses.

FIGS. 19A-19C show cross-sectional side views through the structure ofFIG. 18. Specifically, FIG. 19A shows a cross-section through line A-A′through fin 430; FIG. 19B shows a cross-section through line B-B′through drain 440B; and FIG. 19C shows a cross-sectional side viewthrough line C-C′ through gate electrode 425 and shows gate dielectric427 between gate electrode 425 and fin 430.

FIGS. 20A-20C show the structure of FIGS. 19A-19C following theintroduction of a dielectric material on the first level interconnects;the inverting or flipping of the structure and connection of thestructure to a carrier; the thinning of the substrate and recessing ofthe fin; and the defining of regions of the fin for backside connectionto the source and drain of the device. FIGS. 20A-20C representcross-sections through fin 430, drain 440B, and gate electrode 425,respectively. Referring to FIGS. 20A-20C, in this embodiment, the firstlevel interconnects are passivated by dielectric material 455B such assilicon dioxide or a low k dielectric material. Structure 400 is thenflipped or inverted and connected to carrier 480 such as a semiconductorwafer device side down. Structure 400 may be connected to carrier 480through an adhesive or other bonding technique between dielectricmaterial 455B and carrier 180.

FIGS. 20A-20C also show the structure of FIGS. 19A-19C following theremoval or thinning of substrate 410 by, for example, mechanicalgrinding or etch process to expose a second side or backside of fin 430.In one embodiment, fin 430 is then optionally recessed.

FIGS. 20A-20C further show the structure following the deposition andpatterning of a dielectric material on a backside of fin 430. FIGS.20A-20C show dielectric material 481 of, for example, a silicon dioxideor a low K dielectric material deposited by for example, a blanketdeposition process. Once deposited, dielectric material 481 is patternedby, for example, forming a masking material on a surface of dielectricmaterial 481 with openings or vias opposite, for example, source anddrain regions on an opposite side of fin 430. FIG. 20A shows opening482A through dielectric material 481 oriented on a backside of fin 430corresponding to a source region of the fin (source 440A) and opening482B through dielectric material 481 oriented to a drain region of thefin (drain 440B). FIG. 20B shows that the openings (e.g., opening 482A)have dimensions for a diameter that is greater than a width dimension offin 430. In this manner, a backside of fin 430 as well as sacrificialmaterial 453 are exposed.

FIGS. 21A-21C show the structure of FIGS. 20A-20C following the removalof sacrificial material 453 adjacent opposing sidewalls of fin 430. Inone embodiment, sacrificial material 453 may be removed by an etchprocess with an etchant selective for sacrificial material 453 relativeto dielectric material 455A and 481 and relative to fin 430. FIG. 21Bshows that following a removal of sacrificial material 453, a backsideof fin 430 is exposed as are sidewalls of fin 430 and source 440A.

FIGS. 22A-22C show the structure following an epitaxial growth of amaterial for a backside junction formation and contacts formed on abackside of the device. FIG. 22A shows epitaxially grown material 485Ain opening 482A in a region aligned with a backside of source 440A andepitaxially grown material 485B in opening 482B on fin 430 aligned witha backside of drain 440B. FIG. 22B shows material 485A epitaxially grownon the side walls of fin 430 and connecting with source 440A previouslyformed on a first side or device side of the structure. While anepitaxial growth option is presented, it is appreciated that othermethods described above (doped epitaxial drive-in (FIGS. 12A-15C),implant (FIGS. 16A-17C)) may alternatively be utilized.

FIGS. 22A-22C show the structure following the filling of the viaopenings in dielectric material 481 with a conductive contact materialsuch as a tungsten. FIG. 22A shows contact 486A to epitaxial material485B associated with source 440A and contact metal 486B to epitaxialmaterial 485B associated with drain 440B. FIG. 22B shows contact metal486B to epitaxial material 485B. FIGS. 22A and 22B also show theconnection to source 440A (via contact material) from opposing sides ofthe structure (a first side or device side and a backside or secondside) respectively. Interconnects may now be formed to contacts 486A and486B by, for example, the technique described above with respect todevice side interconnects (see FIGS. 3 and 4A-4C and the accompanyingtext).

FIG. 23 shows a cross-sectional schematic side view of one embodiment ofan assembly including an integrated circuit chip or die connected to apackage substrate. Assembly 500 includes die 510 that may be formed asdescribed above with reference to FIGS. 1-22C. Die 510 includes devicelayer or stratum 515 including a number of devices (e.g., transistordevices). Device stratum 515 includes first side 5150A representing afirst side of the stratum and second side or backside 5150B oppositefirst side 5150A. The transistor devices include, for example, one ormore power transistors and logic circuitry. Connected to device stratum515 of die 510 on a first side are interconnects 520 that, in oneembodiment, include, but are not limited to, a number of conductivemetal lines connected to devices of device stratum 515 from first side5150A. With reference to FIG. 3, interconnect 160A, interconnect 160Band interconnect 170 are representative of a first level ofinterconnects 220 above device stratum 515. Disposed above interconnects520, as viewed, is carrier substrate 540 that is similar to carriersubstrate 180 described above with reference to FIGS. 5A-17. Connectedto devices of die 510 through second side 5100B of the die, in thisembodiment, are interconnects 530 that may be, for example, powerinterconnects (V_(DD), V_(DD)-gated and V_(SS)), logic interconnects orboth. Interconnects 530 on second side or backside 5100B include one ormore levels or rows of metallization. With reference to FIGS. 10A-11,interconnect 190A is representative of a first level of interconnects530 below device stratum 515. FIG. 23 also shows that ones of suchlevel(s) of metallization are connected to contact points (e.g., C4bumps) 550 that are operable to connect die 510 to package 590. FIG. 23further shows V_(DD) and V_(SS) connections to die 510 through packagesubstrate 590.

FIG. 24 is a flow chart of a process to form contacts to source anddrains of a three-dimensional transistor device from a backside andbackside metallization. Referring to FIG. 24, process 600 begins withthe formation of a three-dimensional transistor device on a basesubstrate, the device including a fin extending from the base substrateand a source and drain formed in or on the fin (block 610). Sacrificialmaterial may optionally be formed on a base of the fin as describedabove with reference to FIG. 18. From a first side or device side of thestructure, contacts are formed to the device and device sidemetallization is built (block 620). Following building of metallization,the device is flipped and bonded device side down to a carrier (block625). The base substrate is then removed to expose the fin (block 630)and the fin is optionally recessed (block 635). Dielectric material isthen introduced and patterned on a backside of the device with vias oropenings around the fin to the source and drain (block 640). Ifsacrificial material was previously formed on a base of the fin, thesacrificial material is removed. In one embodiment, epitaxial materialis then introduced on and around the fin to the source and drain (block645). In a second embodiment, a doped epitaxial material is introducedon the fin and dopants in the epitaxial material are driven into the fin(block 650). According to this second embodiment, following dopantdrive-in, the epitaxial material may optionally be removed (block 655).In a third embodiment, an implant is introduced into the fin in sourceand drain regions (block 660). Following one of the above embodiments,the backside vias or openings are filled with contact material to makebackside contacts to source and drain, respectively (block 670).Backside metallization is then optionally built (block 675).

The above embodiments describe the formation of transistor deviceshaving backside contacts. While three-dimensional transistor deviceswere presented, such presentation is not meant to be limiting. Theimplementation of backside transistor contacts and techniques related totheir formation apply to other devices, including nanowire devices andplanar devices.

FIG. 25 illustrates interposer 700 that includes one or moreembodiments. Interposer 700 is an intervening substrate used to bridge afirst substrate 702 to second substrate 704. First substrate 702 may be,for instance, an integrated circuit die. Second substrate 704 may be,for instance, a memory module, a computer motherboard, or anotherintegrated circuit die. Generally, the purpose of interposer 700 is tospread a connection to a wider pitch or to reroute a connection to adifferent connection. For example, an interposer 700 may couple anintegrated circuit die to a ball grid array (BGA) 706 that cansubsequently be coupled to the second substrate 704. In someembodiments, the first and second substrates 702/704 are attached toopposing sides of interposer 700. In other embodiments, the first andsecond substrates 702/704 are attached to the same side of interposer700. In further embodiments, three or more substrates are interconnectedby way of interposer 700.

The interposer 700 may be formed of an epoxy resin, afiberglass-reinforced epoxy resin, a ceramic material, or a polymermaterial such as polyimide. In further implementations, the interposermay be formed of alternate rigid or flexible materials that may includethe same materials described above for use in a semiconductor substrate,such as silicon, germanium, and other group III-V and group IVmaterials.

The interposer may include metal interconnects 708 and vias 710,including but not limited to through-silicon vias (TSVs) 712. Theinterposer 700 may further include embedded devices 714, including bothpassive and active devices. Such devices include, but are not limitedto, capacitors, decoupling capacitors, resistors, inductors, fuses,diodes, transformers, sensors, and electrostatic discharge (ESD)devices. More complex devices such as radio-frequency (RF) devices,power amplifiers, power management devices, antennas, arrays, sensors,and MEMS devices may also be formed on interposer 700.

In accordance with embodiments, apparatuses or processes disclosedherein may be used in the fabrication of interposer 700.

FIG. 26 illustrates a computing device 800 in accordance with oneembodiment. The computing device 800 may include a number of components.In one embodiment, these components are attached to one or moremotherboards. In an alternate embodiment, these components arefabricated onto a single system-on-a-chip (SoC) die rather than amotherboard. The components in the computing device 800 include, but arenot limited to, an integrated circuit die 802 and at least onecommunication chip 808. In some implementations the communication chip808 is fabricated as part of the integrated circuit die 802. Theintegrated circuit die 802 may include a CPU 804 as well as on-diememory 806, often used as cache memory, that can be provided bytechnologies such as embedded DRAM (eDRAM) or spin-transfer torquememory (STTM or STTM-RAM).

Computing device 800 may include other components that may or may not bephysically and electrically coupled to the motherboard or fabricatedwithin an SoC die. These other components include, but are not limitedto, volatile memory 810 (e.g., DRAM), non-volatile memory 812 (e.g., ROMor flash memory), a graphics processing unit 814 (GPU), a digital signalprocessor 816, a crypto processor 842 (a specialized processor thatexecutes cryptographic algorithms within hardware), a chipset 820, anantenna 822, a display or a touchscreen display 824, a touchscreencontroller 826, a battery 828 or other power source, a power amplifier(not shown), a global positioning system (GPS) device 844, a compass830, a motion coprocessor or sensors 832 (that may include anaccelerometer, a gyroscope, and a compass), a speaker 834, a camera 836,user input devices 838 (such as a keyboard, mouse, stylus, andtouchpad), and a mass storage device 840 (such as hard disk drive,compact disk (CD), digital versatile disk (DVD), and so forth).

The communications chip 808 enables wireless communications for thetransfer of data to and from the computing device 800. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 808 may implement anyof a number of wireless standards or protocols, including but notlimited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE,GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The computing device 800 may include a plurality ofcommunication chips 808. For instance, a first communication chip 808may be dedicated to shorter range wireless communications such as Wi-Fiand Bluetooth and a second communication chip 808 may be dedicated tolonger range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The processor 804 of the computing device 800 includes one or moredevices, such as transistors or metal interconnects, that are formed inaccordance with embodiments including backside contacts to device andoptional backside metallization. The term “processor” may refer to anydevice or portion of a device that processes electronic data fromregisters and/or memory to transform that electronic data into otherelectronic data that may be stored in registers and/or memory.

The communication chip 808 may also include one or more devices, such astransistors or metal interconnects, that are formed in accordance withembodiments including backside contacts to device and optional backsidemetallization.

In further embodiments, another component housed within the computingdevice 800 may contain one or more devices, such as transistors or metalinterconnects, that are formed in accordance with implementationsincluding backside contacts to device and optional backsidemetallization.

In various embodiments, the computing device 800 may be a laptopcomputer, a netbook computer, a notebook computer, an ultrabookcomputer, a smartphone, a tablet, a personal digital assistant (PDA), anultra mobile PC, a mobile phone, a desktop computer, a server, aprinter, a scanner, a monitor, a set-top box, an entertainment controlunit, a digital camera, a portable music player, or a digital videorecorder. In further implementations, the computing device 800 may beany other electronic device that processes data.

Examples

Example 1 is an apparatus including

a circuit structure including a device stratum including a plurality ofdevices including a first side and an opposite second side; and a metalinterconnect coupled to at least one of the plurality of devices fromthe second side of the device stratum.

In Example 2, the metal interconnect of the apparatus of Example 1 is afirst metal interconnect, the apparatus further including a second metalinterconnect coupled to the device from the first side of the devicestratum.

In Example 3, the at least one of the plurality of devices of theapparatus of any of Example 1 or 2 includes a transistor device and themetal interconnect is coupled to a source or a drain of the transistordevice.

In Example 4, the metal interconnect of the apparatus of Example 3 is afirst metal interconnect, the apparatus further including a second metalinterconnect coupled to the other of the source or the drain of thetransistor device from the second side of the device stratum.

In Example 5, the metal interconnect of the apparatus of Example 3 is afirst metal interconnect, the apparatus further including a second metalinterconnect coupled to a gate of the transistor device from the firstside of the device stratum.

In Example 6, the one of the source and the drain at a point of couplingto the metal interconnect of the apparatus of Example 3 includes one ofa material epitaxially grown on the one of the source and the drain anda material of the one of the source and the drain modified by one of animplanting of a material and a doping with a material.

Example 7 is a method including forming a transistor device including achannel between a source region and a drain region and a gate electrodeon the channel defining a first side of the device; and forming aninterconnect to one of the source region and the drain region from asecond side of the device.

In Example 8, prior to forming the interconnect to the one of the sourceregion and the drain region, the method of Example 7 includes exposingthe one of the source region and the drain region from the second sideand one of forming a material on the exposed one of the source regionand the drain region and modifying a portion of the one of the sourceregion and the drain region.

In Example 9, the method of Example 8 includes forming a material on theexposed one of the source region and the drain region and such formingincludes epitaxially growing the material.

In Example 10, the method of Example 8 includes modifying a portion ofthe one of the source region and the drain region and modifying includesone of doping and implanting a material into the source region and thedrain region.

In Example 11, forming the transistor device of the method of any ofExamples 7-10 includes forming a fin on a substrate and the sourceregion and the drain region in the fin separated by the channel regionand the gate electrode on the channel region of the fin.

In Example 12, prior to forming the interconnect, the method of Example11 includes exposing an area of the fin from the second side in the oneof the source region and the drain region; and introducing a material onthe exposed fin area or into the fin in the exposed fin area.

In Example 13, introducing a material on the exposed fin area of themethod of Example 12 includes epitaxial growing the material on the fin.

In Example 14, introducing a material into the fin in the exposed finarea of the method of Example 12 includes doping the fin.

In Example 15, the transistor device of the method of any of Examples12-14 is formed on a substrate and exposing an area of the fin from thesecond side includes bonding the substrate to a carrier with thetransistor device facing the carrier; and removing the substrate.

In Example 16, prior to bonding the substrate to the carrier, the methodof any of Examples 12-15 includes forming a spacer material on opposingsidewalls of the one of the source region and the drain region andexposing an area around the fin includes removing the spacer material.

Example 17 is a method including forming a non-planar transistor deviceincluding a fin on a substrate and a source region and a drain region inthe fin separated by a channel region and a gate electrode on thechannel region of the fin defining a first side of the device; bondingthe substrate to a carrier with the transistor device facing thecarrier; removing the substrate to expose a second side of the deviceopposite the first side; exposing an area around the fin from the secondside of the device in one of the source region and the drain region; andforming an interconnect to one of the source region and the drain regionfrom the second side of the device.

In Example 17, prior to forming the interconnect, the method of Example17 includes one of forming a material on the exposed area of the sourceregion and the drain region and modifying a portion of the one of thesource region and the drain region in the exposed area.

In Example 19, the method of Example 18 includes forming a material onthe exposed area of the source region and the drain region and suchforming includes epitaxially growing the material.

In Example 20, the method of Example 18 includes modifying a portion ofthe one of the source region and the drain region and modifying includesone of doping and implanting a material into the source region and thedrain region.

In Example 21, the method of Example 18 includes forming a material onthe exposed one of the source region and the drain region and suchforming includes depositing the material and treating the transistordevice to drive in dopants from the material into the one of the sourceregion and the drain region.

In Example 22, prior to bonding the substrate to the carrier, the methodof any of Examples 18-21 includes forming a spacer material on opposingsidewalls of the one of the source region and the drain region andexposing an area around the fin includes removing the spacer material.

The above description of illustrated implementations, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe invention to the precise forms disclosed. While specificimplementations of, and examples for, the invention are described hereinfor illustrative purposes, various equivalent modifications are possiblewithin the scope, as those skilled in the relevant art will recognize.

These modifications may be made in light of the above detaileddescription. The terms used in the following claims should not beconstrued to limit the invention to the specific implementationsdisclosed in the specification and the claims. Rather, the scope of theinvention is to be determined entirely by the following claims, whichare to be construed in accordance with established doctrines of claiminterpretation.

The invention claimed is:
 1. An apparatus comprising: a circuitstructure comprising a device stratum comprising a plurality of devices,the device stratum comprising a first side and an opposite second side,wherein at least one of the plurality of devices comprises a transistordevice, the transistor device having a gate, a source region, a drainregion, and a channel region between the source region and the drainregion, and wherein the source region and the drain region are both inthe first side of the device stratum; a first metal interconnect coupledto one of the source region or the drain region of the transistor deviceby a first contact from the second side of the device stratum; and asecond metal interconnect coupled to the one of the source region or thedrain region of the transistor device by a second contact from the firstside of the device stratum, wherein the second contact verticallyoverlaps the first contact.
 2. The apparatus of claim 1, furthercomprising a third metal interconnect coupled to the other of the sourceor the drain of the transistor device from the second side of the devicestratum.
 3. The apparatus of claim 1, further comprising a third metalinterconnect coupled to the gate of the transistor device from the firstside of the device stratum.
 4. The apparatus of claim 1, wherein the oneof the source and the drain at a point of coupling to the metalinterconnect comprises one of a material epitaxially grown on the one ofthe source and the drain and a material of the one of the source and thedrain modified by one of an implanting of a material and a doping with amaterial.